The present invention relates to a process for preparing substantially spheroidal alumina particles. The present invention also relates to a process for preparing catalysts from such alumina particles.
Metallic oxides, and particularly alumina, are widely used in the chemical industry, typically as catalysts, catalyst supports, adsorbing agents, etc. For the most of these applications, these oxides are preferably used in the form of spheroidal particles or beads. Among the main advantages of such beads are better wear and crushing strength. The beads are more regularly distributed into the reactors which results in reducing the pressure drop variations of the reactants passing through the reactors.
Several processes have already been proposed for preparing spheroidal alumina particles. One of such processes consists of dispersing an alumina hydrosol as droplets into a medium wherein gelation occurs, and thereafter, subjecting the beads which are obtained in the form of alumina hydrogel, to one or more aging treatments in order to obtain beads having a suitable mechanical resistance. According to another process, an alumina hydrosol is mixed with an ammonium salt and a synthetic polymer or a natural gum, and the mixture is then dispersed into a water-immiscible medium and thereafter subjected to an aging treatment. However, these processes have the disadvantage of needing a very long treatment time which tends to render them uneconomical. Additionally, alumina beads prepared by some of these processes contain high amounts, even excessive on occasion, of impurities which are undesirable when these beads are used as catalysts or catalyst supports.
An object of the present invention is to provide a new and simple method for preparing spheroidal alumina particles.
Another object of the present invention is to provide a method of preparing spheroidal alumina particles whose catalytic activity is not inhibited by impurities.
A further object of the present invention is to provide a new and simple process for preparing spheroidal alumina particles having a uniform size.
Another object of the present invention is to provide a new and improved process which permits ready preparation of unrough alumina beads having a remarkable resistance.